JP2005334701A - Boron-containing water treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boron-containing water treatment method for recovering boron by evaporation and concentration of recycled drainage obtained by adsorbing and removing boron in boron-containing water and desorbing the boron, which can recover boron economically by fractionating and collecting high boron concentration recycled drainage, and reducing the evaporation and concentration volume of the drainage. <P>SOLUTION: In the boron-containing water treatment method for recovering boron by evaporating and concentrating the recycled drainage which is obtained by adsorbing and removing the boron in the boron-containing water by using a granular material where a hydrous oxide of a rare earth element is carried by a porous carrier, and desorbing the boron from the granulated material by an alkali aqueous solution, the concentration of the boron in the recycled drainage is decided from the electric conductivity or pH of the recycled drainage to fractionate and collect the high boron concentration recycled drainage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for treating boron-containing water. More specifically, the present invention relates to a method for treating boron-containing water in which boron is adsorbed and removed from boron-containing water and boron is recovered by evaporating and concentrating the regenerated waste liquid obtained by desorbing boron. The present invention relates to a method for treating boron-containing water, which can fractionate and collect the liquid, reduce the evaporation and concentration of the effluent, and recover the boron economically.

  Boron compounds are used in various applications such as glass, ceramics, enamels, heat insulating materials, electroplating, semiconductor materials, pharmaceuticals, and cosmetics, and wastewater generated from these manufacturing processes contains boron. Boron may also be contained in thermal power plant flue gas desulfurization effluent, geothermal power effluent, waste incineration smoke effluent, landfill disposal leachate, and the like. Since boron in wastewater may cause damage to human health and excessive boron may inhibit the growth of paddy rice and sugar beet, part of the Enforcement Ordinance for Water Pollution Prevention Law was revised. Since July 2015, the drainage standards for boron and its compounds have been set at 10 mg / L for inland waters and 230 mg / L for seawater. In addition, ultrapure water having a boron concentration of ppb or less is required for cleaning water in a semiconductor manufacturing factory. Furthermore, considering the current situation that almost all of the raw material of boron is dependent on imports, the collection of boron in wastewater is important in terms of both removal of harmful substances and reuse of useful substances. For this purpose, various attempts have been made to recover boron by adsorbing and removing boron from boron-containing water and then desorbing it.

  For example, as a method for efficiently separating and recovering high-purity boron from boron-containing wastewater, desorption obtained by desorbing boron adsorbed using a mineral acid solution as an eluent from a boron-selective resin that has adsorbed boron. A method has been proposed in which the separated liquid is passed through an OH type weakly basic anion exchange resin and fractionated into a boron solution and a mineral acid solution (Patent Document 1). As a method for obtaining a high-purity boric acid solution by treating a boron eluent containing an acid radical obtained by regenerating boron adsorbed on an ion exchange resin or a boron selective adsorption resin by passing an acid, the boron eluent containing an acid radical is H A method has been proposed in which a strongly acidic cation exchange resin adjusted to a mold and an anion exchange resin adjusted to an OH type are mixed and passed through an ion exchange tower packed (Patent Document 2). At least two towers filled with an anion exchange resin adjusted to OH type and communicated in series as a purification method of boron eluent having an acid radical to obtain a high purity boron solution with simple process and low equipment cost The ion exchange tower, the step of desorbing the ion exchange resin in the ion exchange tower, and the method of removing the acid radicals by passing the boron eluent containing acid radicals through the deionized ion exchange tower are proposed. (Patent Document 3). As a method for solving the problem of shortening the life of an ion exchange column filled with a strongly acidic cation exchange resin when treating boron-containing water containing acid radicals to recover high purity boron-containing water, acid radicals are included. A method is proposed in which a boron-containing liquid is passed through an anion exchange column packed with an OH type anion exchange resin and then passed through a cation exchange column packed with a strongly acidic cation exchange resin adjusted to an H type. (Patent Document 4). Solves the problem of contamination that occurs when the boron eluate is recovered by passing a mineral acid through a boron selective adsorption resin having N-methylglucamine groups obtained by treating wastewater containing boron. As a means for supplying a high-purity boron eluent to the process, a method has been proposed in which the recovery period is divided into at least two and only the eluent in a period with less impurities is used as a boron recovery solution (patent) Reference 5).

As a method for treating boron-containing water, the amount of chemical use is small, boron-containing water can be economically treated, and boron can be recovered as a valuable material. (B) a desorption step in which boron is adsorbed and removed by contact with an aqueous solution of alkali, and (B) a desorption step in which boron is adsorbed and removed by contacting with an alkaline aqueous solution. E) an evaporation step for evaporating and concentrating a desorption solution containing boron at a high concentration; (D) a crystallization step for crystallizing an alkali metal salt of boric acid in the evaporative concentrate; and (E) an crystallization step of boric acid. A treatment method for boron-containing water having a solid-liquid separation process for separating an alkali metal salt from a liquid was proposed (Patent Document 6). According to this method, it is economically advantageous to collect only a portion having a high boron concentration in the regenerated effluent and reduce the amount of liquid supplied to the evaporator. On the other hand, from the shape such as the size of the head space of the resin tower, it is not possible to uniformly determine how much high concentration boron is desorbed when the liquid is passed after regeneration. Further, when the resin regeneration waste liquid is circulated and reused, the alkali concentration of the regenerant varies somewhat, so the timing at which the high concentration boron is desorbed varies. Therefore, there has been a demand for a means that can determine the boron concentration in the regenerated effluent and efficiently fractionate and collect only the regenerated effluent having a high boron concentration.
JP 2001-104807 A (page 2) JP 2001-335314 A (page 2-3) JP 2001-335315 A (page 2-3) JP 2003-10845 A (page 2) JP 2002-233864 A (second page) JP 2004-50069 (page 2)

  The present invention relates to a method for treating boron-containing water in which boron is adsorbed and removed from boron-containing water and boron is recovered by evaporating and concentrating the regenerated waste liquid obtained by desorbing boron. The object of the present invention is to provide a method for treating boron-containing water that can be collected and reduced in the amount of evaporation and concentration of the drainage to recover boron economically.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have determined that the boron concentration of the regenerated drainage of the granulated body in which the rare earth element hydrous oxide is supported on the porous carrier is By measuring the electrical conductivity or pH of the regenerated wastewater, it is determined when the boron concentration of the regenerated wastewater starts to rise, and the regenerative wastewater having a high boron concentration. It was found that only fractions could be efficiently collected, and the present invention was completed based on this finding.

That is, the present invention
(1) Regenerated waste obtained by adsorbing and removing boron from boron-containing water using a granulated body in which a rare earth element hydrous oxide is supported on a porous carrier, and desorbing boron from the granulated body with an alkaline aqueous solution In the method for treating boron-containing water, which recovers boron by evaporating and concentrating the liquid, the boron concentration in the regenerated wastewater is judged by the electrical conductivity or pH of the regenerated wastewater, and the regenerated wastewater having a high boron concentration is fractionated. A method for treating boron-containing water,
(2) The method for treating boron-containing water according to (1), wherein the aqueous alkali solution is an aqueous sodium hydroxide solution,
(3) When the concentration of the sodium hydroxide aqueous solution is set to 20 g / L or more and the electrical conductivity of the regeneration effluent becomes 500 mS / m or more, fraction collection of the regeneration effluent having a high boron concentration is started (2) The method for treating boron-containing water according to the description,
(4) When the concentration of the sodium hydroxide aqueous solution is 20 g / L or higher and the pH of the regenerated wastewater is 9.5 or higher, fraction collection of the regenerated wastewater having a high boron concentration is started. A method for treating boron-containing water, and
(5) Evaporating and concentrating the regenerated effluent to precipitate an alkali metal salt of boric acid, recovering the alkali metal salt of boric acid by solid-liquid separation, and preparing the aqueous alkali solution to use the separated liquid for boron desorption A method for treating boron-containing water as described in (1),
Is to provide.

  According to the method for treating boron-containing water of the present invention, when desorbing a granulated material in which a porous oxide is supported by a rare earth element-containing hydrous oxide adsorbing boron with an alkaline aqueous solution, the electrical conductivity or pH of the regenerated waste liquid By measuring the starting point of the increase in the boron concentration of the regenerated effluent, fractionally collecting only the regenerated effluent with a high boron concentration, reducing the amount of evaporated liquid, and recovering boron economically it can.

In the method for treating boron-containing water according to the present invention, boron is adsorbed and removed from boron-containing water using a granule in which a rare earth element hydrous oxide is supported on a porous carrier, and the aqueous solution is washed with an alkaline aqueous solution. In the method for treating boron-containing water, which recovers boron by evaporating and concentrating the regenerated effluent obtained by desorbing boron, the boron concentration in the regenerated effluent is determined by the electrical conductivity or pH of the regenerated effluent, and the boron concentration Fractionation of high regenerative drainage.
In the present invention, the hydrous oxide includes both hydrous oxides and hydrous oxides.

  FIG. 1 is a process flow diagram of one embodiment of a boron recovery system to which the method of the present invention is applied. Boron-containing water is passed through a packed column 1 packed with a granule carrying a hydrous oxide of a rare earth element, and boron is adsorbed and removed by contacting with the granule. The treated water from which boron has been adsorbed and removed flows out from the bottom of the packed tower. When the boron concentration of the outflowing treated water reaches a predetermined value, the flow of the boron-containing water is stopped and the process proceeds to the regeneration / desorption process of the granulated body. First, wash water is sent from the top of the packed tower, and the boron-containing water in the packed tower is pushed out. The effluent generated at this time is stored in the dilute effluent storage tank 2 as a dilute effluent, and then again flows through the packed tower together with the boron-containing water. Next, an alkaline aqueous solution is sent from the regenerative liquid storage tank 3 to the packed tower, and the granulated body adsorbing boron is brought into contact with the alkaline aqueous solution to desorb boron. The electrical conductivity or pH of the regenerated drainage generated at this time is measured using an electrical conductivity meter or pH meter 4, and the diluted drainage storage tank is used as the diluted drainage until the electrical conductivity or pH reaches a predetermined value. To send. When the electric conductivity or pH reaches a predetermined value, a signal is sent from the electric conductivity meter or pH meter to the automatic valves 5 and 6, and the automatic drain valve opens and closes to regenerate drainage liquid with high boron concentration. It is sent to the evaporator 7 as a liquid and evaporated and concentrated. When the boron concentration of the regenerated waste liquid decreases after a predetermined time has elapsed, a timer (not shown) is activated to open and close the automatic valve, and the regenerated waste liquid having a low boron concentration is sent to the lean waste liquid storage tank. Switching from the concentrated drainage to the lean drainage by opening and closing the automatic valve can be performed by a signal from the electric conductivity meter.

  The steam generated in the evaporator can be cooled by a cooling condenser, and the generated condensed water can be sent to the regenerated liquid storage tank and used as the water of the alkaline aqueous solution. The evaporated concentrate obtained with the evaporator is sent to the crystallizer 8 and cooled to crystallize the alkali metal salt of boric acid. The suspension in which the alkali metal salt of boric acid is crystallized is sent to the solid-liquid separator 9 and separated into crystals and filtrate of the alkali metal salt of boric acid by solid-liquid separation. The alkali metal salt crystal of boric acid is washed with water in the cleaning device 10 to obtain a pure crystal. Since the filtrate is a concentrated alkaline aqueous solution, it is sent to a regenerating liquid storage tank and used for preparing an alkaline aqueous solution in the desorption process. Since a part of alkali and water is lost by going through each step, alkali and supplementary water are added to the regenerated liquid storage tank to prepare a required amount of an aqueous alkali solution having a predetermined concentration. In the method of the present invention, if necessary, the packed tower can be washed after the desorption step. The drainage generated at this time is stored in the lean drainage storage tank as a lean drainage, and then again flows through the packed tower together with the boron-containing water.

  According to the method of the present invention, the boron concentration of the regenerated effluent generated during the desorption of boron is determined by electric conductivity or pH, and only the regenerated effluent having a high boron concentration is evaporated and concentrated to recover boron. The time and heat energy consumed for evaporative concentration can be saved, and boron can be recovered economically by treating boron-containing water. The regenerated effluent having a low boron concentration is allowed to pass through the packed tower again together with the boron-containing water, and the boron can be adsorbed to the granulated body in which the hydrated oxide of the rare earth element is supported on the porous carrier. Boron can be recovered at a high recovery rate without being lost.

  In the method of the present invention, when the concentration of the aqueous alkaline solution used for regeneration is constant, there is a highly reproducible correlation between the time when the boron concentration of the regeneration drainage starts to increase and the value of electrical conductivity or pH. Therefore, it is possible to determine the boron concentration in the regenerated drainage using the electrical conductivity or pH as an index, and fractionate and collect the regenerated drainage having a high boron concentration. Although there is no particular limitation on the management method of the end point of fraction collection of the regenerated effluent having a high boron concentration, it can be managed by time or electrical conductivity. The larger the amount of the regenerated waste liquid collected as a regenerated waste liquid having a high boron concentration and evaporated and concentrated, the greater the amount of boron recovered per treatment and the higher the recovery rate of the alkaline aqueous solution. However, as the amount of the regenerated waste liquid to be evaporated and concentrated increases, the evaporator becomes larger and the heat energy and time required for evaporation and concentration increase. In the method of the present invention, it is preferable that the collection time of the regeneration drainage having a high boron concentration is approximately the same as the passing time of the regeneration solution. When managing the end point of collection of regenerated drainage by time, the automatic valve can be switched using a timer.

  In the method of the present invention, the amount of the alkaline aqueous solution brought into contact with the granulated body adsorbed with boron is not particularly limited, but is preferably 1 to 5 times the volume of the granulated body, and 2 to 4 times the volume of the granulated body. It is more preferable that When the amount of the alkaline aqueous solution is less than 1 volume times that of the granulated body, the desorption of boron may be insufficient. Boron adsorbed on the granulated body is desorbed with an alkaline aqueous solution of 5 volume times or less of the granulated body, and it is usually unnecessary to use an alkaline aqueous solution exceeding 5 volume times of the granulated body. For example, after the packed tower that has finished the treatment of boron-containing water is washed with 1 to 3 volume times pure water, boron is desorbed and regenerated using 3 volume times alkaline aqueous solution, and further 1 to 3 volume times It can wash | clean using a pure water and can move to the next boron adsorption | suction process. According to the method of the present invention, it is possible to obtain a regenerated effluent usually containing 1,000 to 6,000 mg / L of boron.

  In the method of the present invention, the alkaline aqueous solution used for boron desorption is not particularly limited, and examples thereof include a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution. In these, since the boric-acid compound collect | recovered is a sodium salt, since it can recycle | reuse as a glass raw material, sodium hydroxide aqueous solution can be used suitably. The concentration of the aqueous sodium hydroxide solution used for desorption is preferably 8 to 80 g / L, and more preferably 15 to 40 g / L. When the concentration of the aqueous sodium hydroxide solution is less than 8 g / L, the amount of the required aqueous sodium hydroxide solution becomes excessive, and boron may not be sufficiently desorbed. If the concentration of the aqueous sodium hydroxide solution exceeds 80 g / L, the granulated body carrying the rare earth element hydrous oxide may be deteriorated.

  FIG. 2 shows a structure in which a granulated body in which a rare earth element hydrated oxide is supported on a porous carrier is packed in a tower to adsorb boron, and then boron is desorbed using a sodium hydroxide aqueous solution having a different concentration as a regenerating solution. It is a desorption curve when. As seen in this figure, the boron desorption curve changes depending on the concentration of the regenerated solution even in packed towers of the same shape. Therefore, there is a need for an index that can fractionate and collect a regenerated effluent having a high boron concentration regardless of the concentration of the regenerated solution. In the method of the present invention, the boron concentration in the regenerated drainage is determined using the electrical conductivity or pH of the regenerated drainage as an index, and the time point at which fraction collection of the regenerated wastewater having a high boron concentration is started is determined.

  In the method of the present invention, the aqueous alkaline solution used for boron desorption is a sodium hydroxide aqueous solution having a concentration of 20 g / L or more, and when the electrical conductivity of the regenerated waste liquid is 500 mS / m or more, Fraction collection can be started. FIG. 3 is an example of a graph showing the relationship between the liquid flow rate, the boron concentration, and the electrical conductivity in the boron desorption process. As can be seen in this figure, the electrical conductivity of the regenerated wastewater begins to rise, and when it reaches 500 mS / m, the boron concentration of the regenerated wastewater also begins to rise. The starting point of fraction collection can be determined.

  In the method of the present invention, the aqueous alkaline solution used for boron desorption is a sodium hydroxide aqueous solution having a concentration of 20 g / L or more, and the fraction of the regenerated effluent having a high boron concentration when the pH of the regenerated effluent becomes 9.5 or higher. Sampling can be started. FIG. 4 is an example of a graph showing the relationship between the fluid flow rate, the boron concentration, and the pH in the boron desorption process. As can be seen in this figure, the pH of the regenerated wastewater begins to rise, and when it reaches 9.5, the boron concentration of the regenerated wastewater also begins to rise. The starting point can be determined. However, since the regenerated drainage is strongly alkaline, the electrical conductivity is more preferable than the pH as the management means. It is preferable to switch between the diluted drainage and the concentrated drainage in the actual apparatus by an automatic valve.

  The boron-containing water to which the method of the present invention is applied is not particularly limited, and examples thereof include process wastewater such as pharmaceuticals, cosmetics, soap, and electroplating, and smoke washing wastewater from a garbage incinerator. These wastewaters contain boron as boric acid or borate, and the boron concentration is often several tens to several hundreds mg / L.

  In the method of the present invention, the boron-containing water is preferably brought into contact with a granule carrying a rare earth element hydrous oxide by adjusting the pH to 3 to 12, and the granulation is carried out by adjusting the pH to 4 to 10 More preferably, it is brought into contact with the body. Even if the pH of the boron-containing water is less than 3 or more than 12, there is a possibility that the amount of adsorption decreases.

  There is no particular limitation on the method for producing a granule carrying a rare earth element hydrous oxide used in the method of the present invention. For example, an aqueous solution of a salt of a rare earth element is attached to a carrier, treated with an alkaline aqueous solution, and insoluble on the carrier. This can be produced by depositing and drying the rare earth element hydrous oxide. Examples of rare earth element hydrous oxides include scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. it can. Of these, cerium-containing hydrated oxide can be particularly preferably used. There are no particular limitations on the porous carrier supporting the hydrated oxide of rare earth elements, for example, magnesia, alumina, titania, silica, silica-alumina, zirconia, zeolite, activated carbon, diatomaceous earth, cordierite and other inorganic carriers, polyamide And organic carriers such as cellulose resin, polysulfone, polyacrylonitrile, polyvinyl chloride, and ethylene-vinyl alcohol copolymer.

  In the method of the present invention, there is no particular limitation on the method of bringing boron-containing water into contact with the granule carrying a hydrated oxide of a rare earth element. For example, boron-containing water is passed through a packed tower packed with the granule. Can be contacted. There is no particular limitation on the number of packed towers packed with granulation, for example, only one packed tower can be used, or when a plurality of packed towers are connected in series and the first tower is saturated, A so-called merry-go-round system in which the first tower is removed from the line and the regenerated tower is added to the final stage can be employed. When only one packed tower is used, the process proceeds to the desorption process when the boron concentration of the treated water flowing out of the tower reaches a predetermined drainage standard. In the case of the merry-go-round method, when the boron concentration of the effluent of the first column becomes equal to the inlet concentration, the first column is removed from the packed column and the process proceeds to the desorption process.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
Example 1
Boric acid was dissolved in pure water so that the boron concentration was 150 mg / L, and the pH was adjusted to 7.0 with sodium hydroxide to obtain test water. Test water was passed at a rate of 60 mL / h (SV = 3 h ⁻¹ ) through a glass column filled with 20 mL of a granulated product in which a cerium hydrated oxide was supported on an ethylene-vinyl alcohol copolymer. When water flow was continued for 20 hours and 1,200 mL of test water was passed, the boron concentration of water flowing out of the glass column was 150 mg / L, so water flow was stopped.
Next, the process proceeds to regeneration of the granulated body, and 20 mL of pure water, 100 mL of 20 g / L sodium hydroxide aqueous solution, and 60 mL of pure water are passed in this order at 60 mL / h (SV = 3 h ⁻¹ ) and flow out of the glass column. The effluent water was measured for electrical conductivity, pH and boron concentration. The adsorption and regeneration of boron by the granulated body were repeated 6 times. FIG. 3 shows the relationship between the fluid passing volume, electrical conductivity, and boron concentration in the sixth regeneration, and FIG. 4 shows the relationship between the fluid passing volume, pH, and boron concentration.
As can be seen in FIG. 3, the electrical conductivity of the effluent from the glass column starts to increase, and when sampling is started when it reaches 500 mS / m, it coincides with the start of the increase in the boron concentration of the effluent. A high-concentration regenerative effluent can be fractionated. By setting the end point of fraction collection to be when the flow rate is 3 times from the start of collection, regeneration drainage liquid with a high boron concentration can be collected almost completely.
As can be seen in FIG. 4, when the pH of the effluent from the glass column starts to rise and starts to be collected when it reaches 9.5, it coincides with the beginning of the rise in the boron concentration of the effluent. A high regeneration drainage can be fractionated. By setting the end point of fraction collection to be when the flow rate is 3 times from the start of collection, regeneration drainage liquid with a high boron concentration can be collected almost completely.

Reference example 1
In the same manner as in Example 1, 20 mL / L of test water having a boron concentration of 210 mg / L and a pH of 7 was added to a glass column packed with 20 mL of a granulated product in which a cerium hydrated oxide was supported on an ethylene-vinyl alcohol copolymer. Water was passed through at h (SV = 1 h ⁻¹ ). The water flow was continued for 45 hours, and when 900 mL of test water was passed, the boron concentration of the effluent reached 210 mg / L, so the water flow was stopped.
Next, the process proceeds to regeneration of the granulated body, and 20 mL of pure water, 100 mL of 20 g / L sodium hydroxide aqueous solution, and 60 mL of pure water are passed in this order at 20 mL / h (SV = 1h ⁻¹ ) and flow out of the glass column. Boron concentration was measured for the effluent.
The concentration of the sodium hydroxide aqueous solution was 40 g / L, 80 g / L, 200 g / L or 8 g / L, and the desorbed regeneration of the granulated body adsorbing boron was performed in the same manner. Boron concentration was measured. The results are shown in FIG.
As shown in FIG. 2, even in a glass column in the same state, the boron desorption curve changes depending on the concentration of the sodium hydroxide aqueous solution. It turns out that it is impossible to determine when to start sampling.

  According to the method of the present invention, since only a portion having a high boron concentration can be selectively fractionated from a regenerated effluent generated when boron is desorbed from a granulated body adsorbing boron, recovery of boron Therefore, the amount of liquid to be evaporated and concentrated can be reduced, and boron can be recovered economically.

It is a process flow diagram of one mode of a boron recovery system to which the method of the present invention is applied. It is a desorption curve of boron by an aqueous sodium hydroxide solution. It is an example of the graph which shows the relationship between liquid passing volume, boron concentration, and electrical conductivity. It is an example of the graph which shows the relationship between a fluid passing volume, a boron concentration, and pH.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Packing tower 2 Dilute drainage storage tank 3 Reclaimed liquid storage tank 4 Electrical conductivity meter or pH meter 5 Automatic valve 6 Automatic valve 7 Evaporator 8 Crystallizer 9 Solid-liquid separation device 10 Washing device

Claims (5)

  Adsorbing and removing boron from boron-containing water using a granulated product in which a rare earth element hydrous oxide is supported on a porous carrier, and evaporating the regenerated waste liquid obtained by desorbing boron from the granulated product with an aqueous alkaline solution In the method for treating boron-containing water, which recovers boron by concentrating, determining the boron concentration in the regenerated effluent based on the electrical conductivity or pH of the regenerated effluent, and fractionally collecting the regenerated effluent having a high boron concentration. A method for treating boron-containing water.   The method for treating boron-containing water according to claim 1, wherein the alkaline aqueous solution is an aqueous sodium hydroxide solution.   The boron according to claim 2, wherein fraction collection of the regenerated effluent having a high boron concentration is started when the concentration of the sodium hydroxide aqueous solution is 20 g / L or more and the electrical conductivity of the regenerated effluent becomes 500 mS / m or more. Treatment method of contained water.   The boron-containing water according to claim 2, wherein fraction collection of the regenerated effluent having a high boron concentration is started when the concentration of the aqueous sodium hydroxide solution is 20 g / L or higher and the pH of the regenerated effluent becomes 9.5 or higher. Processing method.   A request for evaporation and concentration of the regenerated effluent to precipitate an alkali metal salt of boric acid, recover the alkali metal salt of boric acid by solid-liquid separation, and use the separated liquid for the preparation of an aqueous alkaline solution used for boron desorption. Item 6. A method for treating boron-containing water according to Item 1.

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